Timing system



March 6, 1934. E. A. SPEAKMAN 1,950,273

TIMING SYSTEM Filed Jan. 8, 1931 2 Sheets-Sheet l March 6, 1934. E. A.SPEAKMAN 1,950,273

TIMING SYSTEM Filed Jan. 8. 1931 2 Sheets-Sheet 2 i fy? I 570M527?" Z-.J- a

Patented Mar. 6, 1934 UNITED STATES PATENT omen 1,950,273 'rnuma SYSTEMEdwin A. Speakman, Nan-berth, Pa. Application January 8, 1931, SerialNo. 507,507

11 Claims. (Cl. 161-18) This invention relates to timing apparatus bywhich the time of travel of a body or object over a certain path may bemeasured or recorded. The general object of the invention is to providea system for this purpose giving a higher degree of accuracy than hasheretofore been obtainable in suchsystems. The invention is particularlyapplicable to timing foot races, horse races, automobile races, or otherraces.

The invention consists primarily of the provision of means responsive tothe sound of a starting gun or other audible signal to start a timingdevice, and means responsive to light to stop the timing device which abeam of light is intercepted by the first object crossing the finishline. Altemately, on oval tracks, the means responsive to light may beused to both start and stop the timing device in response to theinterception of a light beam at the beginning and end of a race.

In order to record accurately the time of any race, it is necessary toeliminate the human element. This is apparent from a study of the humanreaction time which is concerned with the speed of nerve impulses andthe physical response which they produce. Track races are ordinarilytimed with a stop watch operated by ahuman timer. The watch is startedand stopped by the pressure of a spring release. However, there arealways time intervals ,between the times when the race actually startsand stops and the times that the timer pressed the spring release.Observation has shown that these time intervals are each at least 0.16seconds in duration, and that they do not compensate each other becausethe finish of the race is not recorded in the same way as the startthereof. At the start or the race the stop watch is started subsequentto the firing of the starting gun, while at the finish the crossing ofthe finish line is anticipated by the timer. All racing times, as atpresent recorded are, therefore, subject to the human element which maymake them from 0.1 to 0.2 seconds inaccurate. The ideal timer shouldrecord the beginning as well as the end of a race as nearly as possibleinstantaneously, or at least with equal and compensating time lags.

A more specific object of the invention is, therefore, to provide atiming system which will approach as closely to the ideal or perfectsystem as is possible. The timing system is controlled entirely by thestarting and finishing signals themselves, thereby eliminating the humanelesimultaneously.

. the system the over-all operation of the various elements is accurateto within .01 seconds.

The above and other objects of the invention will be more clearlyapparent hereinafter. Reference may be had to the following detaileddescription and the accompanying drawings for a clearer understanding ofa specific embodiment of the invention.

In the drawings: 1

Fig. 1 is a plan view of a race track showing schematically the systemof the invention associated therewith;

Fig. 2 is a schematic wiring diagram of a preferred embodiment of thesystem of the invention;

Fig. 3 is a wiring diagram of a simplified modification of a portion ofthe system;

Fig. 4 is a wiring diagram of a modification of a portion of the systemof Fig. 2; and.

Fig. 5 is-a wiring diagram of modified system. Referring to thedrawings, there is indicated in Fig. 1 a race track 1 which may beadapted for any particular type of race, as previously indicated. Amicrophone 2 is placed adjacent the starting line and is connected totiming apparatus 3. A photo-electric cell 4, or other suitable lightsensitive .device, forms a part of the system and is also connected tothe timing apparatus. This device is placed adjacent the finish line ofthe track, and is adapted to receive a beam of light from a spot-light 5also placed adjacent the finish line on the opposite side of the track.The spotlight may be connected to the timing apparatus so as to receiveits current from a suitable source forming a part of the apparatus, asclearly indicated. Any other suitablelight source may be used in placeof the spot-light. The starter stands about ten yards in front of themicrophone, and the sound from the starting gun reaches the microphoneand the runners ears practically Actuation of the microphone sets intooperation the timing apparatus, which continues to operate until thebeam of light at the finish line is interrupted by the passing of thefirst runner or object to finish.

In Fig. 2 there is disclosed in detail a system designed and constructedin accordance with the invention. As indicated in this figure,microphone 2 is connected in series with the primary winding oftransformer 6 and an adjustable portion of a potentiometer resistance 7.The secondary winding of transformer 6 is in circuit with the contactsof a relay 8, whose purpose will be more apparent hereinafter. Thesystem includes a vacuum tube amplifier 9 which may comprise theventional form. The cathode of the tube may be supplied with energizingcurrent through a suitable transformer 10 from a source of alternatingcurrent 11. The anode or plate supply voltage for the tube is derivedfrom a source of unidirectional voltage 12, which is also adapted tosupply various other operating potentials for the system, as will beclearly apparent as the description proceeds.

Source 12 may have a pair of potentiometer resistances 7 and 13 shuntedacross its terminals and a third potentiometer resistance 14 may beconnected across a portion of potentiometer 7. The lower terminal of thesecondary winding of transformer 6 is connected by means of a variablecontact to potentiometer 14, while the upper terminal of the winding isconnected through the contacts of relay 8, as previously indicated, andthrough switch 15 to the control electrode or grid of tube 9. Thepurpose of switch 15 will be explained later. A resistor 16 has oneterminal connected to grid conductor 1'7, while its other terminal isconnected byv means of a variable contact to potentiometer 13. Thephoto-electric cell 4, or other suitable light sensitive device, has itsanode also connected to conductor 1'7, while its cathode is connectedthrough a current-limiting resistance 19 to potentiometer 7 by means ofa variable contact. The grid cathode circuit of tube 9 is completed bymeans of conductor 18, connected between the midpoint of secondarywinding of transformer 10 and an intermediate point of potentiometerresistance '7.

The plate circuit of the amplifying tube includes the winding of a relay20, which is adapted to be energized by a suitable increase in the platecurrent of the tube to operate the timing device circuit. This relayfunctions to control a circuit which includes in series switch 21, thewinding of a polarized relay 22, the contacts of a slow-actingdouble-pole relay 23, source of polarizing potential 24 and acurrent-limiting resistor 25. The contacts of polarized relay 22 controlthe circuit of the indicating device 26, which may take the form of anysuitable electric clock adapted to start and stop instantaneously uponthe closure or opening of the circuit. A. suitable source of alternatingcurrent 27 supplies the necessary operating energy to the clock. If alow voltage timing device is used, a suitable step-down transformer maybe used. This source also supplies energizing current for relays 8 and23. .The circuit through timing device 26 includes a resistor 29.

The amplifying circuit is so designed that the timing device can only bestarted by the proper sound entering the microphone, and stopped by theinterception of the light beam on the photocell. The same vacuum tube isused to amplify the impulse, first from the microphone and then from thephoto-electric cell. While various individual power sources for thevarious elements of the system have been shown for clarity ofillustration, it will be apparent that a single commercial A. C. sourcemay be used and the necessary D. C. potentials obtained by siutablerectifying devices.

It will be noted that a constant current from source 12 will normallyfiow through resistor 16, causing a voltage drop thereacross. This dropmay be controlled differentially by means of potentiometers 13 and 14.The normal grid bias for the tube is at the same time controlled bymeans of these potentiometers. It will be apusual three-electrodeamplifying tube of conparent that these potentiometers are included ,inparallel paths from the cathode to the grid of the tube when relay 8 isclosed, and that by virtue of the current flowing in these pathsopposing potentials are set up between the grid and cathode of the tube.These potentials are preferably adjusted by means of the potentiometersto provide sufficient negative bias on the grid to give practically zeroplate current. Adjustment of potentiometers 13 and 14 enables theplacing of a suitable negative bias on the anode of the photo-cell withrespect to its cathode, thereby rendering the cell inoperative. Sincepotentiometers 13 and 14 are also included in parallel paths between thecell electrodes, their adjustment will effect the biasing of the cellalso. The normal current flow through the microphone may be controlledby means of its adjustable contact along potentiometer '7. It Will benoted that by means of a plurality of suitable potentiometers, as shown,a-

give less flexibility and less fine adjustment.

Such a modification will be described later.

Considering now the operation of the system,

the circuit of the secondary winding of a transformer 6 is normallyclosed through the contacts of relay 8 which is deenergized. A negativebiasing potential is, therefore, applied to the grid of the amplifyingtube, as described above. A negative biasing potential is also appliedto the photo-cell anode, as explained above, thus causing the cell to beinoperative while the microphone circuit is closed. The adjusted gridbias of the tube makes is sensitive to the gun sound only and not toextraneous noises which might enter the microphone.

Since the sound wave from the gun consists of a compression followed bya rarefaction, the current through the microphone and transformer 6first increases and then decreases. A complete cycle of potentialvariation thus results across the secondary of transformer 6. are soarranged that the grid side of the secondary receives the positivecharge first and then the negative. The grid is, therefore, firsteffected positively. The positive potential overcomes the negative gridbias and causes appreciable plate current flow. The increase in platecurrent causes sufficient energization of relay 20 to operate the same,thereby completing the circuit through the-winding of polarized relay22.

The contacts of relay 23 are normally biased by 7 means of a suitablesprin or the like, to the right. Current of a suitable polarity,therefore, fiows to the polarized relay which closes its 'contacts tocomplete the circuit through device 26 The connections and resistor 29.The timing device, therefore,

starts and continues to operate until its circuit is subsequentlyopened, as will appear later.

It will be noted that the polarized relay also closes a circuit forrelay 8, thereby energizing the same and opening the circuit of thesecondary winding of transformer 6. This renders the microphoneinoperative and opens one of the parallel biasing paths for the tube andcell. As a result, the negative potential previously established on theanode of the photo-cell is removed and a positive potential is placedthereon by potentiometer 13. The voltage drop across resistor 16 due tothe electron flow in the cell then causes a negative potential to beapplied to the "grid of the amplifying tube and causes a drop in theplate current. Therefore, relay is deenergized and opens the circuit ofpolarized relay 22. However, the contacts of this relay remain closed,because its armature is unbiased. In "the meantime, relay 23 has alsobeen energized by the closure of the contacts of relay 22, as will beclearly obvious. Relay 23, therefore, functions to reversethe polarityof the current to be subsequently applied to polarized relay 22. Relay23 is slow acting so that it will act after relay 20 has closed andopened its contacts. The action of relay 20 is speeded up by makingrelay 8 fast acting, since it is the operation of relay 8 that causesrelay 20 to operate in each case. If relay 23 were to reverse thepolarity of thepolarized relay before relay 20 could open its contacts,the polarized relay would immediately open its contacts prematurely,thereby stopping the timing device. In fact, a thorough study will makeit evident that with the contacts of relay 20 always closed, both relays23 and 22 will operate back and forth continuously.

When the light received by the photo-cell is intercepted, as by a runnercrossing the finish A line, the electron emission from the cathode ofrendering the microphone operative and again placing the originalnegative bias on the grid of the amplifying tube. A decrease in theplate current of the tube, therefore, results and relay 20 isdeenergized. Since relay 23 is also deenergi'zed, its contacts are drawnto the right by the biasing spring and the polarity applied to thepolarized relay is proper for the repeating of the operation of thesystem. Thus the system resets itself. It should be noted also thatcompletion of the circuit through secondary winding of transformer 6causes the application of the original negative potential to the anodeof the photo-cell, thereby again rendering it inoperative. Thephoto-cell is, therefore, immediately rendered inoperative by the firstinpulse which it imparts to the amplifying tube. Interception of thelight beam by the runners following has no effect. This is also true ofthe microphone which is cut out by the opening of relay 8 upon the firstimpulse from the microphone. The shifting from the microphone to thephoto-cell and vice versa is, therefore, accomplished automatically bythe opening and closing of relay 8. Although the operation of the timingsystem during the race is entirely automatic, it is necessary to turnthe hand of the indicating device back to the starting point to preparefor the next race. This may be accomplished by repeated pressure on abutton to advance the hand to the desired position.

As previously stated, a single potentiometer could be used to obtain thevarious operating potentials of the system, and a disclosure of such asimplified modification will probably afford a clearer understanding ofthe invention. Fig. 3 shows this simplified arrangement, it beingunderstood that the portion of the system not shown in this figure isidentical with and operates in the same manner as the correspondingportion of the system of Fig. 2. In Fig. 3, a single potentiometer 7a isused in conjunction with source 12, and the various movable contacts ofthe system are associated with the single potentiometer resistance atsuitable points. A negative biasing potential may be established uponthe grid of tube 9 by relative adjustment of contacts a and c, thepotential across the portion of the potentiometer between these pointsbeing effective to give the desired potential. Likewise, a negativebiasing potential may be established upon the anode of photo-cell 4 byrelative adjustment of contacts a and b. By virtue of the circuitthrough resistor 16 parallel paths containing opposing potentials existbetween the cell and tube electrodes as before. The portions 0, d and b,d of the potentiometer which tend to place positive biases on the tubeand cell respectively are such, however, that they do not balance orovercome the negative biasing potentials. Furthermore, such tendency isopposed by the potential drop across resistor 16.

In operation, of the system, relay 8 (not shown) is normally closed andthe desired negative biasing potentials are, therefore, established uponthe tube and cell as described above.- Practically zero plate currentflows in the output circuit of the tube and the cell isrenderedinoperative. When sound from the starting gun actuates the microphone,the positive impulse across the secondary of transformer 6 overcomes thebias of the tube and causes arise in plate current, thereby operatingrelay 20. The timing device and associated circuits (not shown) whichare associated with relay 20 in the same manner as in the system of Fig.2, function as previously described when the relay operates. Relay 8 isenergized as previously explained and opens the circuit of thetransformer secondary, thereby removing the bias from the tube and thephoto- 7 cell. The voltage drop across resistor 16, due to the electronfiow in the photo-cell then causes I a negative potential to be appliedto the grid of the amplifying tube and causes a drop in its platecurrent to deene'rgize relay 20.

When the light of the photo-cell is intercepted at the finish of a race,the electron emission of the cell is less and the voltage drop acrossresistor 16 decreases. A less negative or more positive potential is,therefore, applied to the grid of the tube and an increase of its platecurrent takes place to again operate relay 20 and stop the timing deviceas before. Thus, it is seen that this modified system operates upon thesame principle as that of Fig. 2, but is simplified to a great extent.

However, it affords less flexibility of control and less fineadjustment.

Were it not for the fact that relay 20 operates both at the start and atthe finish of the race, a large source of error would be caused by therelay action in the closing of its contacts. However, the closing of thecontacts of the relay is caused by precisely the same amount of currentin each instance, and any time lag at the start is exactly duplicated atthe finish. Relay 22 which controls the clock introduces a small timelag while its contacts are closing. This lag can hardly be duplicated atthe opening of the contacts, since the clock circuit is broken beforethe contacts have opened to the full-width of the gap. An error is,therefore, present depending upon the distance between the contacts.This error may be inch.

the timing device. gized through the contacts of relay 22 and its con-In order to eliminate the undesired error just mentioned, which iscaused by relay 22, the timing device system of Fig. 4 may beincorporated into the systems of Figs. 2 and 3. In this figure, only themodified portion of the system is shown, since the remainder may beidentical with either that of Fig. 2 or Fig. 3 and functions in the samemanner. In this instance, an additional doublethrow polarized relay 30is included in the circuit controlled by relay 20. A slow-acting relay31 is connected in parallel with the windings of relays 8 and 23 to asuitable A. C. source of potential 32 through the contacts of polarizedrelay 22. The contacts of relay 31 control the circuit of the timingdevice 26. The operation of the timing device is also controlled bypolarized relay 30 and resistor 33.

Considering the operation of this modification, the timing device isstarted upon the breaking of the contacts of relay 30 on the right andstopped upon the breaking of its left hand contact. Thus, the timingdevice is started and stopped bp precisely the same motion of the relaycontacts in each case, viz., by the breaking of the contacts. Initially,the contacts of relays 30 and 31 are closed on the right. The effect ofthe contacts of relay 30 is to shunt resistance 33 directly across thetiming device. Current from source 27 passes through the resistance andthe timing device remains inoperative.

Upon energization of the winding of relay 30, due to the momentaryclosing of contacts of relay 20, as previously explained, the contactsof relay 30 are broken at the right as the movable contact moves fromright to left. Resistance 33 is, therefore, cut out so that currentpasses through the closed contacts of relay 31 to the timing device,which starts immediately. The movable contact of relay 30 continues tomove to the left and closes. The slow-acting relay 31 then opens itscontacts, allowing the current to the timing device to pass through thecontacts of relay 30, which are closed on the left. Relay 31 is operatedby having its winding energized through the contacts of relay 22, whosewinding is energized simultaneously with that of relay 30. The currentthen passes through the closed contacts of relay 30 to the clock whichcontinues running.-

When the contacts of relay 20 again close and energize relays 30 and 22,the movable contact of relay 30 moves to the right, thereby breaking thecircuit to the timing device which stops immediately. This contactcontinues to the right, closing the shunt circuit through resistance 33about Relay 31 is no longer enertacts are, therefore, closed. Theinitial condition is, therefore, instituted and the mechanism is readyto repeat operation. It is essential that relay 31 and its contacts beclosed while the movable "contact of relay 30 is moved from right toleft, since if the contacts of relay 31 were opened during this time,the circuit to the timing device would not be completed until themovable contact of relay 30 engaged the left-hand contact. The breakingof the left-hand contacts of relay 30 stops the timing device, and,therefore, the conright. If the contacts of relay 31 should close duringthis time, the circuit to the timing device would be completed, causingit to again start running. Relay. 31 must, therefore, have a time lagsuch that it operates'two secondsafter relay 30 in each case. By havingthe timing device stopped and started by the breaking of contacts, timelag due to the motion of moving parts is eliminated. It is, thereforeseen that the modified system eliminates the previously discussedobjectionable error due to the operation of the contacts of relay 22.

In the case of long races where the runners proceed around an oval trackseveral times, a slight change in the operation of the systems describedis necessary. After the-timing device has started, switch 21 must beopened. When the light beam is intercepted afterthe first lap of therace, the contacts of relay 20 close but complete no circuit, due to thebreak at the switch. Hence, the timing device continues running. On thelast lap, when the leading runner is perhaps fifty yards from thefinish, switch 21 may be closed by the operator and the mechanism isready to function to stop the timing device when the light beam isintercepted, as previously explained. For short dashes, however, suchas100, 220' and 440 yard races, no manual operation is necessary. It is inthese short races that an accurate timer is most needed.

It is also important to note that in using the system with oval tracks,which are commonly used for automobile or horse races, the timing devicemay be started and stopped entirely by the interception of a light beam.If switch 15 is opened, the microphone circuit is permanently disabledand the only impulses which would operate the clock would be those fromthe photocell whenever its beam of light is intercepted. It is importantto note that successive interception will alternately stop and start thetiming device automatically. Therefore, in races on oval tracks, theoperation of the systemcould be initiated by interception of the lightbeam and stopped by a second interception of the light beam. While ithardly seems likely that any instance would arise in which it would bedesired to use the microphone alone to start and stop circuiting thecontacts of relay 8 permanently.

In Fig. 5- there is shown a modified system in which a single relay 34is utilized to take the place of relays 8 and 20 of thepreviously-described systems. This modified system also differs slightlyin the operation of the photo-cell and also eliminates the necessity fora plurality of relays and-circuits in connection with the timing device.In this system, a single potentiometer 7ahas been utilized to obtain thevarious potentials for clarity of illustration, but it will be apparentthat a plurality of potentiometers may be used as in the system of Fig.2. The connections of. the photo-cell electrodes are'reversed in thisinstance, the anode being connected by means of a variable contact tothe potentiometer, while the cathode is connected to grid conductor 17.A short-circuiting switch 35 and a current limiting resistor 36 areshunted about the photo-cell for a purpose to be described later.double-acting relay having both left hand and right hand contacts, andwhen deenergized, the right hand contacts are closed' by virtue of asuitable biasing spring 37 or the like.

Relay 34 is a" Considering the operation of this system, relay 34 isnormally deenergized and its right hand contacts are closed. The closureof these contacts corresponds to the normal closed condition of relay 8of the previously described systems, and suitable biasing potentials maybe. placed upon the tube and cell electrodes. A negative biasingpotential may be established upon the grid of tube 9 by relativeadjustment of contacts a and 0', while an operating potential for theelectrodes of the photo-cell may be established by suitable adjustmentof contacts a" and d. It will be noted that in thiscase a positivepotential is established on the photo-cell anode with respect to -itscathode. However, the cell is rendered practically inoperative, due tothe potential drop across resistor 16 caused by the constant flow ofcurrent therethrough, such potential drop opposing the potential tendingto render the cell operative. The negative bias upon the grid of tube 9is sufficiently high that the potential drop across resistor 16 cannotovercome the bias to cause energization of the tube even if a variationin light intensity on the tube should cause a variation in the potentialdrop.

- When the microphone is actuated by the sound of the starting gun asbefore, the positive impulse across the secondary of transformer 6overcomes the negative grid bias of the tube, causing an increase inplate current of the tube. Relay 34 is, therefore, energized and opensits right .hand contacts and closes its left hand contacts.

Thus, the circuit of the transformer secondary is opened and the circuitof the timing device 26 is closed. The opening of the transformer secofthe tube to maintain relay 34 energized. The

timing device, therefore, continues to operate until the finish of therace when it is rendered inoperative as follows. Interception of lightto the photo-cell at the finish of the race causes 1a decrease in thecell current through resistor sufiiciently to deener'gize the same.Relay 34 then opens its left hand and closes its right hand contacts,thus stopping the timing device and closing the circuit of the secondarytransformer 63. The original starting condition is, therefore, obtained,the system automatically resetting itself for repeated operation.

Switch 35 and resistor 36 are provided for operation in the case of ovaltracks where the light beam upon the photo-cell'is interrupted severaltimes before the end of the race. In such case, switch 35 may be closedby the operator after the timing device has been started in the mannerdescribed. This switch short circuits the photocell through the currentlimiting resistor, and

when the light beam is intercepted at the end iamplitude to maintainrelay 34 energized. During the last lap of the race when the racers areapproaching the finish line, switch 35 may beopened and the cell therebyrendered operative and functions to stop the timing device, as abovedescribed.

While I have disclosed herein for the purpose of illustration thespecific details of several embodiments of the invention, it will beapparent .that various changes within the scope of the invention arepossible without departing from the spirit of the same. Therefore, it isto be understood that only such limitations as are contained within theappended claims are to be imposed upon the invention. i

I claim:

1. A timing system for measuring the time of travel of a body over acertain path, comprising a timing device, means comprising a deviceresponsive to a certain form of atmospheric wave energy for startingsaid device at the beginning and stopping it at the end of travel ofsaid body over said path.

2. A timing system for measuring the time of travel of a body over acertain path, comprising a timing device, means for controlling saiddevice, means normally operative for controlling said first means tostart said device at the beginning of travel of said body over saidpath, means normally inoperative for controlling said first means tostop said device at the end of travel of said body over said path, meansfor rendering said second means inoperative and said third meansoperative simultaneously with the starting of said device, and means forreturning each of said means to normal condition simultaneously with thestopping of said device.

3. A timing system for measuring the time of travel of a body over acertain path, comprising a timing device, means for controlling saiddevice, and means responsive to a certain form of atmospheric waveenergy for controlling said first means to start said device at thebeginning andto stop it at the end of travel of said body over saidpath.

4. A timing system for measuring the time of travel of a body over acertain path, comprising a timing device, means for controlling saiddevice, means normally operative for controlling said first means tostart said device at the be- 115 ginning of travel of said body oversaid path, means normally inoperative for controlling said first meansto stop said device at the end of travel of said body over said path,and means controlled by said first means for rendering said sec- 120 ondmeans inoperative and said third means operative simultaneously with thestarting of said device.

5. A timing system for measuring the time of travel of a body over acertain path, comprising a timing device, means for controlling saiddevice, means normally operative and responsive to one form ofwaveenergy for controlling said first means to start said device at thebeginning of travel of said body over said path, means nor- 130 mally.inoperative and responsive to a different form of wave energy forcontrolling said first means to stop said device at the end of travel Iof said body over said path, and means controlled by said first meansfor rendering said sec- 135 ond means inoperative and said third meansoperative simultaneously with thestarting of said device.

6. A timing system for measuring the time of travel of a body over acertain path, comprising a timing device, means for controllingsaiddevice, means normally operative and responsive to sound for controllingsaid first means to start said device at the beginning .of travel ofsaid body over said path, means normally inoperative and responsive tolight for controlling said first means to stop said device at the end oftravel of said body over said path, and means controlled by said firstmeans for rendering said second means inoperative and said third meansoperative simultaneously with the starting of said device. I

7. A timing system, comprising a timing device, means comprising a pairof electric discharge devices one controllable by the other forcontrolling the operation of said timing device, means for normallyrendering said devices ineffective, means for rendering one of saiddevices effective to start said timing device, and means for renderingthe other of said devices effective to control said one device to stopsaid timing device.

8. A timing system, comprising a timing device, means comprising a pairof electric discharge devices one controllable by the other forcontrolling the operation of said timing device, means for normallyrendering said devices ineffective, means for rendering one of saiddevices effective to start said timing device, and means controllable atwill for. rendering the other of said devices efiective to control saidone device to stop said timing device.

9. A timing system, comprising a timing device, means comprising a pairof devices for controlling the operation of said timing device, meansfor applying a non-operating potential to said devices to normallyrender the same ineffective, means for applying a greater operatingpotential to one of said devices to render the same effective to startsaid timing device, means for removing said non-operating potential, andmeans responsive to said removal for applying an operating potential tothe other of said pair of devices to render it efiective to control saidone device to stop said timing device.

10. In a timing system, an electrically controlled timing device, meansnormally rendering said device inoperative, a slow-acting circuitcontrol device normally tending to render said timing device operative,a dOUbIQj-thIOW circuit control device normally maintaining said meanseifective, and adapted when energized to render said means inefiectiveand to subsequently close the circuit of said timing device, and meansfor simultaneously energizing said circuit control devices, whereby saidtiming device is immediately operated and is maintained operative bysaid slowacting device until said double-throw device has closed thecircuit of said timing device.

11. In a timing system an electrically controlled timing device, meansnormally rendering said device inoperative, a slow-acting circuit control device normally tending to render said.tim-' ing device operative,a double-throw polarized relay normally maintaining said meansefiective, and adapted when energized to render said means inefiectiveand to subsequently close the circuit of'said timing device, a controlcircuit including the energizing winding of said polarized relay, asource of voltage for said control circuit, means for reversing thepolarity of said source, a second polarized relay included in saidcontrol circuit, and an energizing circuit for said slow-acting deviceand said" reversing means controlled by said second polarized relay.

EDWIN A SPEAKMAN.

